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Past terrestrial hydroclimate sensitivity controlled by Earth system feedbacks

R. Feng·T. Bhattacharya·B. Otto-Bliesner·E. Brady·A. M. Haywood·J. Tindall·S. J. Hunter·A. Abe- Ouchi·W.-L. Chan·M. Kageyama·C. Contoux·C. Guo·X. Li·G. Lohmann·C. Stepanek·N. Tan·Q. Zhang·Z. Zhang·Z. Han·J.R. Williams·D. J. Lunt·Harry J. Dowsett·Deepak Chandan·W. Richard Peltier
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Abstract

Despite tectonic conditions and atmospheric CO 2 levels ( pCO 2 ) similar to those of present-day, geological reconstructions from the mid-Pliocene (3.3-3.0 Ma) document high lake levels in the Sahel and mesic conditions in subtropical Eurasia, suggesting drastic reorganizations of subtropical terrestrial hydroclimate during this interval. Here, using a compilation of proxy data and multi-model paleoclimate simulations, we show that the mid-Pliocene hydroclimate state is not driven by direct CO 2 radiative forcing but by a loss of northern high-latitude ice sheets and continental greening. These ice sheet and vegetation changes are long-term Earth system feedbacks to elevated pCO 2 . Further, the moist conditions in the Sahel and subtropical Eurasia during the mid-Pliocene are a product of enhanced tropospheric humidity and a stationary wave response to the surface warming pattern, which varies strongly with land cover changes. These findings highlight the potential for amplified terrestrial hydroclimate responses over long timescales to a sustained CO 2 forcing.

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R. Feng, T. Bhattacharya, B. Otto-Bliesner, E. Brady, A. M. Haywood, J. Tindall, S. J. Hunter, A. Abe- Ouchi, W.-L. Chan, M. Kageyama, C. Contoux, C. Guo, X. Li, G. Lohmann, C. Stepanek, N. Tan, Q. Zhang, Z. Zhang, Z. Han, J.R. Williams, D. J. Lunt, Harry J. Dowsett, Deepak Chandan, W. Richard Peltier. 2022-03-14. Past terrestrial hydroclimate sensitivity controlled by Earth system feedbacks. https://doi.org/10.1038/s41467-022-28814-7

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